The present invention relates in general to a manual transmission and particularly to a twin clutch manual transmission having automatic clutches for respective gear range groups and useful for performing automatic shifting by switching of the automatic clutches between an engaged condition and a disengaged condition and by alternative selection of a gear range between the gear range groups. More particularly, the present invention relates to a shift fork position detecting device for a manual transmission such as a twin-clutch manual transmission.
Heretofore, such a twin clutch manual transmission is known as disclosed in Unexamined Japanese Patent Publication No. 8-320054. The twin clutch manual transmission includes a first input shaft and second input shaft to which rotational power of an engine is selectively supplied by way of respective automatic transmissions. The second input shaft is hollow and is rotatably fitted on the first shaft. The first input shaft protrudes from the second input shaft so as to have a protruded rear end portion. Between the protruded rear end portion of the first input shaft and a counter shaft in parallel with the first and second input shafts are disposed gear trains of an even number gear range group that are selectively operated by respective synchronizers so as to transmit power therethrough and gear trains of an odd number gear range group that are selectively operated so as to transmit power therethrough by respective synchronizers. Rotational power having been changed in speed in accordance with a selected gear range is taken out from the front end of the counter shaft that is positioned adjacent the engine.
Such a twin clutch manual transmission is adapted so that under a condition where a gear range of one of the gear range groups is selected and its corresponding automatic clutch is engaged, selection of any gear range of the other of the gear range groups is not performed. Upon shifting from the selected gear range, a gear range of the other gear range group is selected by a corresponding synchronizer and its corresponding automatic clutch is disengaged. Then, the automatic clutch corresponding to the one gear range group is disengaged and the automatic clutch corresponding to the other gear range group is engaged, i.e., switching of the clutches between an engaged condition and a disengaged condition is performed, together with alternative selection of the gear range between the both gear range groups. By this, although the transmission is a manual transmission, it can perform an automatic shifting.
FIGS. 4 to 7 show a shift fork assembly according to an earlier technology which can be used in such a twin clutch manual transmission. The shift fork assembly includes shift fork 56 having shift fork main body 54 straddling a nearly semi-circular part of circular outer circumferential groove 53 of coupling sleeve 52 of synchronizer 51 and engagement portion 55 engaged in outer circumferential groove 53 and thereby gripping the same.
In such shift fork 56, shift fork main body 54 is slidably mounted on shift shaft 57. By moving shift fork main body 54 axially of shift shaft 57 by actuator 58 coupled with shift fork 56, coupling sleeve 52 of synchronizer 51 is moved axially thereof for thereby engaging, under a synchronizing operation of synchronizer ring 59, a splined inner circumferential periphery of coupling sleeve 52 with clutch gear 60 or 61 of any one of the gear trains provided to the counter shaft and the input shaft, thereby selecting a gear range.